1. Field of the Invention
This invention relates to a fan with an inlet mounting plane and an outlet mounting plane for installation on a wall element, which has a ventilation opening, of a switchgear cabinet, wherein a fan unit has fastening flanges on the inlet and outlet sides which are identical and are oriented parallel with respect to each other and is assembled from the fan unit and an additional housing.
2. Description of Related Art
Fan units of this type are known in diverse embodiments, wherein they can be directly connected with the wall element by one or the other fastening flange. Such fan units are conventional and can be provided in various sizes and use requirements. As a rule, the air flow is oriented the same in the area of the inlet and outlet fastening planes, as well as vertically with respect to these planes, as can be determined from PCT International Application WO 96/41511.
As is known from Patent Abstracts of Japan, volume 18, No. 480 (E1603), Sep. 8, 1994, and Japanese Patent Reference JP 06 164175A (Ricoh Cp. Ltd.), in such a fan unit only fastening planes extending parallel with each other can also be attached with an intermediate housing as a fan of the type previously mentioned wherein, however, its outlet plane continues to extend parallel with the wall element and does not cause a change in the flow direction of the fan unit. The direction of flow continues to remain vertically oriented with respect to the fastening planes and to the ventilation opening of the wall element.
As U.S. Pat. No. 4,648,007 shows, such fan units can be fastened in a housing to be ventilated at areas, which have various inclinations, of a wall element in order to change the direction of the air flow. For reasons of space this is not practical in connection with a flat wall element of a switchgear cabinet, because the fan unit must be attached at different locations of the wall element, depending on the way the switchgear cabinet is equipped.
It is also known to employ specially designed ventilators in cooling devices. In this case the inlet and the outlet fastening planes of the fan unit extend at an acute angle with each other, wherein the action of the fan as a suction or pressure fan is predetermined, as shown in PCT International Application WO 88/01127. Furthermore, depending on the location where they are used, the fans can also be designed as a fan with a filter, as shown in U.S. Pat. No. 5,528,454.
Particular requirements must be met when using such fans in the interior of a switchgear cabinet. The air will need to be aspirated from different locations in the cabinet interior and must also be supplied to the cabinet interior at different locations. This presumes a flexible installation, which must be matched to the existing conditions. In this case the wall element is often designed to be double-walled and is used as an air conduit, and is often even used as a heat exchanger housing. The wall element made of an outer leaf and an inner leaf forms a very flat air conduit which leads to congestion of the air, since the air flow which is aspirated and fed into the air conduit impacts on the outer wall element, which results in eddy formation. Moreover, the aspirating direction of the air flow cannot be optimally matched to the existing circumstances if fan units, which are customary in commerce, are to be used.